1. Field of the Invention
The present invention relates generally to an auxiliary drainage system for relieving and eliminating water problems associated with the foundation of an existing building, and, more particularly, to a method for dealing with ground water problems without the need to carefully hand-dig a trench immediately adjacent the exterior surface of the foundation to expose the exterior surface of the foundation to permit its being treated and waterproofed.
2. Prior Art
Accepted conventional waterproofing techniques call for a trench to be dug carefully, usually by hand, immediately adjacent to the exterior surface of the foundation of a building to expose the foundation's exterior surface for repair and treatment. The ditch is dug to a level below that of the top of the basement floor of the building to expose and permit servicing of the building's footer drain tile system. If the footer drain tile system is found to be clogged or in need of repair, appropriate steps are taken to put this system back into good operating condition.
When such a trench must be dug, it may be necessary to temporarily remove, and sometimes destroy, existing bushes, trees and other foundation plantings. Sometimes the digging of such a trench also requires removal and rebuilding of sections of sidewalks, stairs and driveways. In other situations, it is possible to gain access to the required area of foundation wall by tunneling under some of the foundation plantings and/or such existing structures as extend alongside the foundation. Digging the necessary trenches and tunnels is a time consuming and relatively expensive undertaking which usually must be done by hand. Power equipment such as a backhoe usually cannot be used to perform this work in view of the delicate nature of the work and the possibility of damage to the building.
A problem with all storm drainage systems is that particulate material such as leaves, small pieces of roofing and other kinds of debris tend to enter the system through downspouts. This particulate material accumulates in storm drainage tile and diminishes the effective size of the tile. TABLE 1 presents a tabulation of the square feet of roof area which can be served by various nominal sizes of drain tile laid at slopes of 1/8 inch, 1/4 inch and 1/2 inch per foot of length of the tile, respectively, assuming a four inch per hour downpour. If half of the operable diameter of a drain tile is blocked by an accumulation of debris, its effective carrying capacity will be cut in half and, as a minimum, the figures presented in TABLE 1 will need to be halved. Moreover, in the presence of a very significant downpour, some of the debris may be transported from place to place in a drain line, and may tend to collect at a common location causing a blockage of the entire system.
TABLE 1 ______________________________________ Square footage of roof are served by tile of various nominal sizes laid at slopes of 1/8 inch, 1/4 inch and 1/2 inch per foot of tile length. Nominal Diameter Square Footage of Roof Area Served of Drain Tile 1/8" per ft 1/4" per ft 1/2" per ft ______________________________________ 3 822 1,160 1,644 4 1,880 2,650 3,760 5 3,340 4,720 6,680 6 5,350 7,550 10,700 8 11,500 16,300 23,000 10 20,700 29,200 41,400 12 33,300 47,000 66,600 15 59,500 84,000 119,000 ______________________________________
While the installation of gutter guards and gutter-carried screens is helpful in diminishing the quantity of debris washed into drain lines through downspouts, the quantity of debris which continues to enter drain lines is unacceptably high and significantly reduces the capacity of these lines.
3. The Referenced Patent
The disclosure of the referenced patent is incorporated herein inasmuch as it presents the best and most accepted technique utilized in present-day practice for thoroughly repairing and waterproofing the foundation of an existing building, and for preventing the reoccurrence of ground water problems associated with a foundation of a building. The referenced patent relates to a method of overcoming the problem of water seeping into the basement of a dwelling or other building structure, whereby (1) the foundation is treated to fill its hollow spaces, especially hollow spaces in the vicinity of cracks or other structural damage or deterioration, (2) the footer drain line system of the building is serviced and restructured if need be to put it in proper form for trouble-free operation, (3) clean-outs are provided at spaced locations around the foundation for future checking and servicing of the footer drain line system, and (4) porous reservoirs are formed from particulate material such as stone in lower portions of the trenches or tunnels which have been dug about the foundation of the building. The porous reservoirs provide a system of open passages for ducting water to the footer drain line system, and for providing regions where water may temporarily accumulate harmlessly in a situation of heavy rainfall or backup of the storm drain line which serves the building.
The referenced patent also discusses the advantages which can result from constructing a manhole at the juncture of the footer drain line system and the storm drain line. In some situations it is desirable to install a check valve in the storm drain line at the location of the manhole to prevent the storm drain line from backing up into the building's footer drain line system. In other situations, it is desirable to have the footer drain line system discharge directly into the manhole, and to utilize a sump pump to transfer water from the manhole to the storm drain line.
While the waterproofing system disclosed in the referenced patent continues to represent the most preferred approach to take in dealing with basement waterproofing problems, there are situations where the digging of a ditch immediately adjacent the outer face of a foundation wall is unduly expensive and/or would unacceptably require the removal or destruction of valuable foundation plantings or existing structures. The present invention addresses these situations.